The present invention relates to a speaker device, and particularly relates to a speaker device for vibrating a diaphragm in response to an electrical signal to produce sound.
A loudspeaker is widely used as a conversion means for converting an electrical signal into the sound. In particular, a dynamic speaker is designed so that a voice coil wound about a bobbin is disposed within a gap of a magnetic circuit constituting a driving means, the vibration in a direction of axis received by the voice coil is transmitted to the diaphragm, whereby the vibration in response to the electrical signal is produced by the diaphragm to produce the sound in response to the electrical signal.
It is difficult for such a loudspeaker to reproduce a low sound to a high sound evenly. Thus, generally, a plurality of loudspeakers are combined. For example, a loudspeaker for a low sound and a loudspeaker for a high sound constitute a speaker device. Accordingly, output from an amplifier is supplied to the respective loudspeakers through a dividing network comprising a plurality of filters, and a reproducing band is divided by the dividing network.
Such a dividing network as described comprises a combination of filters such as a lowpass filter, a bandpass filter, a highpass filter and so on, and is constituted by a combination of an inductance coil and a condenser. A coil for such filters as described, that is, a network coil is mounted, as a part separately from the loudspeaker, in a predetermined position of the speaker device.
For example, as shown in FIG. 1, a loudspeaker 1 is mounted so as to close an aperture of a baffle plate 3 on the front surface side of a speaker box 2, a terminal plate 5 is mounted on a rear cover 4, and a network coil 6 is mounted internally of the terminal plate 5.
In the conventional speaker device as described above, the network coil is formed from a single independent part, and the filter coil is formed from a combination of a coil and a condenser to divide a band of an electric signal supplied to the corresponding loudspeaker. The conventional network coil is an air-core coil, which is mounted on the terminal plate 5, as shown in FIG. 1, for example.
The mounting as described above poses a problem that when magnetic metal such as iron is present nearby, the inductance changes under the influence thereof. Further, since the network coil is used as a single part, the number of parts increases when the speaker device is assembled.
The present invention has been accomplished in view of the problem as noted above. It is an object of the present invention to provide a speaker device adapted to wind and mount a network coil about a loudspeaker.
According to the present invention, there is provided a speaker device for vibrating a diaphragm in response to an electrical signal to produce sound, wherein a network coil is wound about a driving part for vibrating a diaphragm.
The driving part comprises a magnetic circuit, and a voice coil disposed in an air gap of the magnetic circuit, and the network coil may be wound about the outer peripheral portion of the magnetic circuit. Further, the device may be designed so that a cover is mounted so as to cover the magnetic circuit, a groove is formed around in the outer circumferential surface of the cover, and the network coil is wound about within the groove. Further, the network coil may constitute a core of the network coil. Further, the network coil may be wound about so as to be located around the plate of the magnetic circuit. Furthermore, the cover is formed of a magnetic material, and the network coil may be wound about the outer circumferential surface of the cover. Moreover, the cover is formed of a synthetic resin, a ring formed of a magnetic material is mounted on the cover, and the network coil may be wound about externally of the ring.
According to the present invention, the network coil is mounted to be wound about the driving part for vibrating the diaphragm, and a filter is constituted by the network coil to restrict the band of a signal supplied to the loudspeaker.